Lens-grinding machine



H. W. HILL.

LENS GRINDING MACHINE.

APPLICATION FILED MAR. 12. 1920.

436,255. Patented Nov. 211, 1922,

w a A. a

I J M a L my 4 fi ATTORNEYS Patented Nov. 21, 1922.

HARRY W. HILL, OF SOUTHBRIDGE, IEASSACHUSETTS .lSSIG-NOR TO AMERICAN OPTI- CAL COMPANY, OF SOUTHBRIDGE, MASSACHUSETTS, A VOLUNTARY ASSOCIATION OF MASSACHUSETTS.

LENS-GRINDING MACHINE.

Application filed March 12, 1920. Serial No. 365,25.

To all whom it may concern:

Be it known that I, HARRY ,W. HILL, a citizen of the United States, residing at Southbridge, in the county of Worcester and State of Massachusetts, have invented certain new and useful Improvements in Lens-Grinding Machines, of which the following is a specification.

This invention relates to improvements in lens grinding machines and has particular reference to new and improved means for retaining the lenses in position during the grinding operation.

The leading object of the present invention is the provision of a novel and improved machine which will greatly facilitate the production of lenses, in that it will make possible to at one time grind a plurality of lenses and at the same time eliminate the necessity for constructing a special pitch block for retaining the lenses, will eliminate the securing and removing of the lenses from the block and the cleaning operations necessary to render the lenses usable after they have been so disengaged.

A further object of the invention is the provision of a machine particularly adapted for use in the grinding of countersinks of bifocal lenses or the like which shall greatly increase the speed of production of these lenses and which shall be substantially automatic in operation, requiring minimum attention during the grinding.

Other objects and advantages of my improved construction should be readily apparent from the following specification taken in connection with the accompanying drawings, and it will be understood that I may make any modifications in the specific details of construction shown and described within the scope of the appended claims without departing from or exceeding the spirit of the invention.

Figure I represents a vertical sectional view of a machine embodying my improvements.

Figure II represents a plan view of the lens block and lenses in position therein.

Figure III represents a sectional view as on the line IIIIII ofFigure II.

In the drawings, the numeral 1 designates the main frame of the machine having journaled in the lower portion thereof the rotat able spindle 2 having a cone portion 3 engaged in the socket 4: 0f the block or lens receiving member 5. This member 5 is provided with a plurality of recesses 6 shown in Figure II as four in number, which are of size to just receive the lenses 7 andpreferably of such depth that the upper face of the lens 7 will fit substantially flush with the non-recessed portion of the block 5. The particular advantage gained by this construction' is that there is no appreciable interruption of the continuity of the inner face of the block, with the result that when a quantity of abrasive, such as emery in suspension in water or the like, is contained within the bowl and the bowl is rotated as by power applied to the pulley 9 on the spindle 2, there will be practically a smooth inner face to the bowl block allowing the material to swirl freely and to be thrown outward by the centrifugal action. The advantage of this outward throwing of the material by centrifugal action, resides in the fact that there is a scraper 10, so called, carried by the frame 1, depending within the bowl and into the path of the centrifugally thrown material interrupting the throw of material to cause it to shoot inward towards the center and thus keep a continuous flow of the abrasive from center to edge for the grinding operation.

As has been mentioned, the particular apparatus illustrated is especially designed for use in grinding countersinks in lens blanks 7 for the formation of bifocal lenses the lens thus being ground only at a relatively small portion, as at- 11, while the remainder is unground. This type of grinding particularly lends itself to my invention since I may here make use of the clamp members 12 which fit over a pair of the adjacent lenses and are secured in position by the clamp screw 13 while held against turning movement as by the pair of spaced abut- ;inent members 14 between which the clamp ts. a

By reference to Figure III the way in which the clamp engages and retains the lenses will be clearly understood, and it will be seen that it is below the height of the center portion where the countersink 11 is to be ground, as indicated by the dotted line in Figure III, and that consequently the grinding tool or lap 15 will be above and entirely out of engagement with the clamp masses members during the grinding operation and these members will serve to securely retain the lenses within the seats or recesses 6 of the block. The grinding operation is effected by rotation of the block bearing the lenses in combination with oscillation of the grinding member 15 as through the bearing 17 as by the weight 18 and being reciprocated as by the cam 19 engaged within the cam shaft 20 actuating the spindle either in both directions or in one direction, when it may be actuated in the opposite direction as by the spring 21, in either event a transverse or shifting movement of some sort preferably being applied to the grinding member which is in addition free to spin on the pin 16 due to difference in friction on the two sides by the contact of the lenses therewith as they rotate. a broken up grinding motion being thus effected which will produce the desired shape and curve of countersinks within the several blocks without scratches, wave effects or the like.

I would further call particular attention to the relationship of the lenses on the block as more particularly illustrated in Figure I, from which it will be seen that the shape of the block and of the lens receiving recesses formed therein is such that the several blanks of glass are not supported as a continuation one of the other, or conforming to a common upper curve on their grinding surfaces, but are supported to be tilted with respect to each other and to present as the relatively highest point an eccentric portion of each blank so that on account of the particu lar arrangement and supporting of the blanks the countersinks or grinding opera-- tion performed on the blanks will be at a predetermined point and will cover a substantially predetermined area when the grinding is completed, which area as shown is entirely within the limits of the blank, although it will be understood that the tilting may be modified as desired to cause the grinding to extend out over the edge to be near the central portion of the blank, or any other preferred position.

From the foregoing description taken in connection with the accompanying drawings the construction of my improved machine, and more specifically the method of securing the lenses in place, will be readily appreciated. In place of it being necessary to individually mold a pitch blank for each grinding operation, as has been required in the past, it is merely necessary to construct the cast iron block with lens receiving recesses and the lenses themselves in place of being stuck onto the block with adhesive may be placed into the recesses and locked in position by clamp screws, thus facilitating their subsequent removal. The lenses may be removed and will have no pitch or adhesive sticking to them, requiring subsequent washing and cleaning operations as is the case where they are secured to the block by pitch as in the previously employed method.

I claim:

Y '1. A block for use in the formation of bifocal lenses, comprising a bowl like member having a plurality of recesses therein, clamp members disposed intermediate adjacent re cesses having portions adapted to overlie the edges of the recesses for engaging and securing a pair of lenses within the recesses, and means for drawing the clamp members into operative relation to the lenses.

2. A block for use in the formation of bifocal lenses comprising a bowl like member having a plurality of recesses formed therein having convex seats for lens blanks, clamp members disposed intermediate adjacent recesses having portions adapted to overlie the edges of the recesses for engaging and securing a pair of lenses in position on the seats, and means for drawing the clamp members into operative relation to the seats.

3. The combination with a lens block hav i'ng recesses formed therein, of a bar clamp member for securing lenses within the recesses, adapted to extend between and bear upon the edges of a pair of lenses, and means engaging the bar for locking the same against rotative disengaging movement.

4. A block for use in the formation of hifocal lenses comprising a bowl like member having a plurality of recesses formed. therein having convex seats for lens blanks, clamp members disposed intermediate adjacent recesses having portions adapted to overlie the edges of the recesses for engaging and securing a pair of lenses in position on the seats, meansfor drawing the clamp members into operative relation to the seats, and abutment members carried by the block and engaging the clamp members for preventing rotation thereof.

5. In a device of the character described, the combination with a block having lens receiving recesses formed therein, of clamp members intermediate the recesses having portions overlying the recesses for engagement with the lenses, said clamp members being bevelled whereby their edges will lie substantially flush with the surface of the lenses when in operative position.

In testimony whereof I have aflixed my signature, in presence of two witnesses.

HARRY W. HILL. 

